Physical, Biochemical, and Biologic Properties of Fat Graft Processed via Different Methods.

Clinical use of autologous fat for correction of soft-tissue defects in cosmetic and reconstructive procedures has grown in popularity. Graft processing is implicated as one of the variable factors affecting quality, viability, and subsequent graft survival. This study analyzed the in vitro physical and biologic characteristics of lipoaspirate processed using different techniques. METHODS: Fresh lipoaspirates from patients with informed consent were processed by 4 methods: decantation, centrifugation, the REVOLVE System, and PureGraft. Processed fat grafts were analyzed for yield, composition, tissue particle size and morphology, and viability and function of adipocytes and stem cells. Fat tissue harvested from waste containers of REVOLVE and PureGraft and trapped on REVOLVE paddles was also evaluated. RESULTS: Grafts produced by the filtration systems contained the highest percentage of fat tissue, whereas those from decantation contained the lowest percentage, although they have the highest volume yield. In addition, grafts from REVOLVE and PureGraft showed more large-sized particles (>1000 µm) than those from decantation or centrifugation. REVOLVE also preserved significantly higher populations of viable and functional adipocytes and stromal vascular fraction cells when compared with other processing methods. Tissue particles in waste containers of REVOLVE and PureGraft were mostly (>85%) <300 µm and demonstrated a minimal number of viable adipocytes and stem cells. Fat tissues trapped on REVOLVE paddles contained a higher percentage of noninjectable and fibrous collagen bundles. CONCLUSION: Different processing methods result in fat grafts with varying physical and biologic properties, which may contribute to fat graft viability and retention in vivo.

Preclinical evaluations of acellular biological conduits for peripheral nerve regeneration.

Various types of natural biological conduits have been investigated as alternatives to the current surgical standard approach for peripheral nerve injuries. Autologous nerve graft, the current gold standard for peripheral nerve damage, is limited by clinical challenges such as donor-site morbidity and limited availability. The purpose of this study was to evaluate the efficacy of using acellular xenographic conduits (nerve, artery, and dermis) for the repair of a 1.2 cm critical size defect of peripheral nerve in a rodent model. Four months post surgery, the animal group receiving acellular artery as a nerve conduit showed excellent physiological outcome in terms of the prevention of muscle atrophy and foot ulcer. Histological assessment of the bridged site revealed excellent axon regeneration, as opposed to the nonrepaired control group or the group receiving dermal conduit. Finally, the study evaluated the potential improvement via the addition of undifferentiated mesenchymal stem cells into the artery conduit during the bridging procedure. The mesenchymal stem cell-dosed artery conduit group resulted in significantly higher concentration of regenerated axons over artery conduit alone, and exhibited accelerated muscle atrophy rescue. Our results demonstrated that xenographic artery conduits promoted excellent axonal regeneration with highly promising clinical relevance.

Porcine incisional hernia model: Evaluation of biologically derived intact extracellular matrix repairs.

We compared fascial wounds repaired with non-cross-linked intact porcine-derived acellular dermal matrix versus primary closure in a large-animal hernia model. Incisional hernias were created in Yucatan pigs and repaired after 3 weeks via open technique with suture-only primary closure or intraperitoneally placed porcine-derived acellular dermal matrix. Progressive changes in mechanical and biological properties of porcine-derived acellular dermal matrix and repair sites were assessed. Porcine-derived acellular dermal matrix-repaired hernias of additional animals were evaluated 2 and 4 weeks post incision to assess porcine-derived acellular dermal matrix regenerative potential and biomechanical changes. Hernias repaired with primary closure showed substantially more scarring and bone hyperplasia along the incision line. Mechanical remodeling of porcine-derived acellular dermal matrix was noted over time. Porcine-derived acellular dermal matrix elastic modulus and ultimate tensile stress were similar to fascia at 6 weeks. The biology of porcine-derived acellular dermal matrix-reinforced animals was more similar to native abdominal wall versus that with primary closure. In this study, porcine-derived acellular dermal matrix-reinforced repairs provided more complete wound healing response compared with primary closure.